1.5 The Theory of Plate Tectonics

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Vocabulary

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Scientific theory: Is a well-tested concept that explains a wide range of observations.
Plate tectonics: Is the geological theory that states that pieces of the Earth's lithosphere are in constant, slow motion, driven by convection currents in the mantle.
Faults: Brakes in the Earths crust where rocks have slipped past each other.
Transform boundary: Is a place where two plates slipped past each other, moving in oposite directions.
Divergent boundary: Is a place where two plates move apart, or diverge.
Convergent boundary: I a place where two plates come together, or converge.

Outline

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A Theory of Plate Motion

• The theory of plate tectonics
  • explains the formations, movement, and subduction of the Earths plates.
  • Plates of the lithosphere float on top of the asthenoshere.
  • Plates cannot move without effecting the other plates surrounding it.

Plate Boundaries

• There are three kinds of plate boundaries:
  • transform boundaries,
    • Earthquakes occur frequently around transform boundaries.
  • divergent boundaries,
    • occur on land and under water,
    • sometimes divergent boundaries can create a rift valley.
  • and convergent boundaries.
    • Convergent boundaries result in a collision.

The Continent' Slow Dance

• Plates move about one to ten centimeters per year.
• The North American and Eurasian plates are floating apart at a rate 2.5 centimeters per year.

Plate tectonics